Enemies and Diseases.

Monkeys, rats, and parrots are here and in all tropical countries the subject of much complaint, and if the plantation is remote from towns or in the forest, their depredations can only be held in check by the constant presence of well-armed hunter or watchman. Of the more serious enemies with which we have to deal, pernicious insects and in particular those that attack the wood of the tree, everything has yet to be learned.

Mr. Charles N. Banks, an accomplished entomologist, now stationed at Maao, Occidental Negros, is making a close study of the life history of the insect enemies of cacao, and through his researches it is hoped that much light will be thrown upon the whole subject and that ways will be devised to overcome and prevent the depredations of these insect pests. The most formidable insect that has so far been encountered is a beetle, which pierces and deposits its eggs within the bark. When the worm hatches, it enters the wood and traverses it longitudinally until it is ready to assume the mature or beetle state, when it comes to the surface and makes its escape. These worms will frequently riddle an entire branch and even enter the trunk. The apertures that the beetle makes for the laying of its eggs are so small—more minute than the head of a pin—that discovery and probing for the worm with a fine wire is not as fruitful of results as has been claimed.

Of one thing, however, we are positively assured, i. e., that the epoch of ripening of the cacao fruit is the time when its powerful fragrance serves to attract the greatest number of these beetles and many other noxious insects to the grove. This, too, is the time when the most constant and abundant supply of labor is on the plantation and when vast numbers of these insects can be caught and destroyed. The building of small fires at night in the groves, as commonly practiced here and in many tropical countries, is attended with some benefits. Lately, in India, this remedy has been subject to an improvement that gives promise of results which will in time minimize the ravages of insect pests. It is in placing powerful acetylene lights over broad, shallow vats of water overlaid with mineral oil or petroleum. Some of these lamps now made under recent patents yield a light of dazzling brilliancy, and if well distributed would doubtless lure millions of insects to their death. The cheap cost of the fuel also makes the remedy available for trial by every planter.

There is a small hemipterous insect which stings the fruit when about two-thirds grown, and deposits its eggs within. For this class of insects M. A. Tonduz, who has issued publications on the diseases of cacao in Venezuela, recommends washing the fruit with salt water, and against the attacks of beetles in general by painting the tree stem and branches with Bordeaux mixture, or with the vassiliére insecticide, of which the basis is a combination of whale-oil soap and petroleum suspended in lime wash. There can be no possible virtue in the former, except as a preventive against possible fungous diseases; of the sanitive value of the latter we can also afford to be skeptical, as the mechanical sealing of the borer’s holes, and thereby cutting off the air supply, would only result in driving the worm sooner to the surface. The odor of petroleum and particularly of whale-oil soap is so repellent, however, to most insects that its prophylactic virtues would undoubtedly be great.

The Philippine Islands appear to be so far singularly exempt from the very many cryptogamic or fungous diseases, blights, mildews, rusts, and cankers that have played havoc with cacao-growing in many countries. That we should enjoy continued immunity will depend greatly upon securing seeds or young plants only from noninfested districts or from reputable dealers, who will carefully disinfect any shipments, and to supplement this by a close microscopical examination upon arrival and the immediate burning of any suspected shipments.

Another general precaution that will be taken by every planter who aims to maintain the best condition in his orchard is the gathering and burning of all prunings or trimmings from the orchard, whether they are diseased or not. Decaying wood of any kind is a field for special activity for insect life and fungous growth, and the sooner it is destroyed the better.

On this account it is customary in some countries to remove the fruit pods from the field. But unless diseased, or unless they are to be returned after the harvest, they should be buried upon the land for their manurial value.

Manuring.

There are few cultivated crops that make less drain upon soil fertility than cacao, and few drafts upon the land are so easily and inexpensively returned. From an examination made of detailed analyses by many authors and covering many regions, it may be broadly stated that an average crop of cacao in the most-favored districts is about 9 piculs per hectare, and that of the three all-important elements of nitrogen, phosphoric acid, and potash, a total of slightly more than 4.2 kilograms is removed in each picul of cured seeds harvested. These 37 kilos of plant food that are annually taken from each hectare may be roughly subdivided as follows:

• 18 kilos of nitrogen,
• 10 kilos of potash,
• 9 kilos of phosphoric acid.

On this basis, after the plantation is in full bearing, we would have to make good with standard fertilizers each year for each hectare about 220 kilos of nitrate of soda, or, if the plantation was shaded with leguminous trees, only one-half that amount, or 110 kilos. Of potash salts, say the sulphate, only one-half that amount, or 55 kilos, if the plantation was unshaded. If, however, it was shaded, as the leguminous trees are all heavy feeders of potash, we would have to double the amount and use 110 kilos.

In any case, as fixed nitrogen always represents a cost quite double that of potash, from an economical standpoint the planter is still the gainer who supplies potash to the shade trees. There still remains phosphoric acid, which, in the form of the best superphosphate of lime, would require 55 kilos for unshaded orchards, and about 70 if dap-dap, Pionciana, or any leguminous tree was grown in the orchard. These three ingredients may be thoroughly incorporated and used as a top dressing and lightly harrowed in about each tree.

If the commercial nitrates can not be readily obtained, then recourse must be had to the sparing use of farm manures. Until the bearing age these may be used freely, but after that with caution and discrimination. Although I have seen trees here that have been bearing continuously for twenty-two years, I have been unable to find so much as one that to the knowledge of the oldest resident has ever been fertilized in any way, yet, notwithstanding our lack of knowledge of local conditions, it seems perfectly safe to predicate that liberal manuring with stable manure or highly ammoniated fertilizers would insure a rank, succulent growth that is always prejudicial to the best and heaviest